My install on Mac Snow Leopard using DW CS4 went flawless!
I didn't experience the issue Tom had so I am not sure if it is a OS specific problem.
I did, though, have to delete the macfilecache thing.
A couple of quick suggestions:
On the dialogue box where you set up the file browser, I would strongly recommend that WA add a note underneath the file browser prompt that states something like, "Remember that adequate permissions have to be set on this folder to upload".
If you don't add that little line, I can already tell what will happen to the forum support thread... people will be on here screaming that the product doesn't work amongst other nonsense.
My other suggestion is - if room in the dialogue box to have some brief notice about what the "advanced file manager" is. It only says that a database is needed but even I am not sure what it exactly is and I am fairly well versed in FCKeditor.
The interface looks tremendous and is much faster than the previous iRite. Overall, I am very pleased with the extension's functionality and ease of use.